imaging of small renal masses mark e. lockhart, md, mph university of alabama at birmingham july 28,...
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Imaging of Small Renal Masses
Mark E. Lockhart, MD, MPHMark E. Lockhart, MD, MPH
University of Alabama at BirminghamUniversity of Alabama at Birmingham
July 28, 2012July 28, 2012
Objectives
Discuss basic imaging findings Discuss basic imaging findings associated with small renal massesassociated with small renal masses
Highlight recent radiology Highlight recent radiology recommendations of incidental renal recommendations of incidental renal lesionslesions
Konnak JW, J of Uro 1985; Ozen H, Br J Uro 1993
Renal “Masses”
Most are now incidental on US, CT and Most are now incidental on US, CT and MRIMRI
Most are simple cysts and require no actionMost are simple cysts and require no action Incidental RCC have lower stage of Incidental RCC have lower stage of
malignancy (82% stage 1) than malignancy (82% stage 1) than symptomatic (37%)symptomatic (37%)
Column of Bertin
Actually a septum Actually a septum rather than a columnrather than a column
Junction of interpolar Junction of interpolar region and poleregion and pole
May be slightly May be slightly echogenic relative to echogenic relative to adjacent cortexadjacent cortex
How to evaluate a renal mass
Is it fatty?Is it fatty?Gross fat is less than -20 HUGross fat is less than -20 HUConsider angiomyolipoma or liposarcomaConsider angiomyolipoma or liposarcoma
Is it cystic?Is it cystic?Is it fluid density (-10 to 20 HU)Is it fluid density (-10 to 20 HU)Use Bosniak criteriaUse Bosniak criteria
Does it enhance?Does it enhance?Borderline is 15-20 HU changeBorderline is 15-20 HU changeMetastases, IVC clot, lymphadenopathy?Metastases, IVC clot, lymphadenopathy?
Angiomyolipoma
10% of patients 10% of patients with tuberous with tuberous sclerosissclerosis
80% of TS have 80% of TS have AMLAML
If exophytic then If exophytic then look for wedge of look for wedge of fat in cortexfat in cortex
Bosniak MA, Rad 1986 Curry NS, AJR 2000
Bosniak Classification
Bosniak MA.Bosniak MA. The current radiological approach to renal The current radiological approach to renal cysts. Radiology 1986;158:1 -10cysts. Radiology 1986;158:1 -10
Type 1 – simple cystType 1 – simple cyst Type 2 – mildly complex; likely benignType 2 – mildly complex; likely benign Type 3 – complex; worrisomeType 3 – complex; worrisome Type 4 – cystic neoplasmType 4 – cystic neoplasm
Cannot show Cannot show enhancementenhancement
Evaluation for Evaluation for de-enhancement de-enhancement can be useful if can be useful if same scanner on same scanner on same daysame day
Bosniak II: Small hyperdense
Bosniak IIF
Slightly more complex cysts that cannot be Slightly more complex cysts that cannot be neatly classified as category II or III neatly classified as category II or III lesions.lesions.
Perceived but Perceived but nonmeasureable nonmeasureable septal enhancement septal enhancement
stable on f/u
Curry NS, AJR 2000; Berland 2012
Bosniak III
Indeterminate cystic massesIndeterminate cystic masses Thickened irregular walls or septa with Thickened irregular walls or septa with
measureable enhancementmeasureable enhancement 25-59% chance malignancy 25-59% chance malignancy Recent work at UAB suggests lower rateRecent work at UAB suggests lower rate Percutaneous biopsy is controversialPercutaneous biopsy is controversial
Bosniak MA, Rad 1986 Curry NS, AJR 2000
Bosniak IV
Malignant cystic masses. Malignant cystic masses. 80-100% likelihood of malignancy80-100% likelihood of malignancy Findings similar to Bosniak III but also Findings similar to Bosniak III but also
have enhancing soft-tissue components have enhancing soft-tissue components adjacent to, but independent of, the wall or adjacent to, but independent of, the wall or septum. septum.
Bosniak IV: Thick enhance septa
Multilocular cystic Multilocular cystic nephromanephroma
Look for extension Look for extension into collecting into collecting systemsystem
No venous extensionNo venous extension
Renal Cell Carcinoma
Most common renal malignancyMost common renal malignancy More common in malesMore common in males Arises in renal cortex – often disrupts renal Arises in renal cortex – often disrupts renal
contour even when smallcontour even when small Bilateral in only 2%Bilateral in only 2% Calcifications in 25-30%Calcifications in 25-30%
Oncocytoma mimics RCC
Both are solid and Both are solid and disrupt cortical margindisrupt cortical margin
Both can enhanceBoth can enhance
Both can have central Both can have central scarscar
Urothelial Carcinoma Central renal mass Central renal mass
with mild ehancementwith mild ehancement
Rarely calcifiedRarely calcified
Extension into Extension into collecting systemcollecting system
Nodal metastasesNodal metastases
Lipid-Poor AML
Mildly hyperdense on Mildly hyperdense on CTCT
Low T2 signal. Does Low T2 signal. Does not drop signal on not drop signal on opposed phase MRIopposed phase MRI
Enhances similar to Enhances similar to RCCRCC
Renal Lymphoma
Focal mass(es)Focal mass(es) Infiltrative massInfiltrative mass Renal hilar massRenal hilar mass Perinephric rindPerinephric rind
Rarely only site Rarely only site of involvementof involvement
Management
ACR white paper on incidental renal massesACR white paper on incidental renal masses Cystic based on Bosniak criteriaCystic based on Bosniak criteria Solid based on sizeSolid based on size
>3cm, surgery>3cm, surgery1-3cm, surgery (may biopsy if 1-3cm, surgery (may biopsy if
hyperdense, homogenously enhancing)hyperdense, homogenously enhancing)<1cm, observe until 1cm<1cm, observe until 1cm
Berland JACR 2010
Management
Slight different criteria if high risk patient or Slight different criteria if high risk patient or limited life expectancylimited life expectancy
Small mass more likely benignSmall mass more likely benign Still rare risk of metastases in small massStill rare risk of metastases in small mass
Lack of morphologic change over 5 years Lack of morphologic change over 5 years suggests benignsuggests benign
Berland JACR 2010
Management different for VHL
Lower malignant potential
Resect when largest 3 cm
Acquired Cystic Renal Disease
Much higher risk of Much higher risk of RCC developmentRCC development
Consider any solid Consider any solid mass as suspiciousmass as suspicious
Summary
Small renal masses are a common Small renal masses are a common diagnostic challengediagnostic challenge
A few have characteristic features that can A few have characteristic features that can help the diagnosishelp the diagnosis
Know the imaging criteriaKnow the imaging criteria